Creating Order
Specific Learning Outcomes
By the end of this unit you should be able to:
Name each of the processes represented by the letters MRSGREN.
Explain how each of the processes in MRSGREN are carried out in living things.
Be able to make a key to classify a group of objects
Name the 5 kingdoms
Be able to label diagrams of a binocular and monocular microscope
List the characteristics of animals (i.e. members of the Animal Kingdom)
Name the 5 families of vertebrates
Give the characteristics for the 5 families of vertebrates
Give the characteristics of Arthropods
Be able to compare and contrast any 2 groups of animals and explain why they are grouped differently.
Know where the major organs are found in the human body
Understand how cells, tissues and organs are related
Know the purpose of the circulatory system
Know how blood flows through the heart and around the body
Be able to label the chambers and main blood vessels of the heart
Know the purpose of the excretory system
Be able to label a diagram of a kidney
Know the purpose of the respiratory system
Be able to label a diagram of the lungs
Living things
Living things are called organisms. All living things on Earth are thought to be descendants of a single, common ancestor - the great-grandmother of us all, probably about 3 billion years ago.
If we found life somewhere else, how would we recognise it as life?
Scientists thing that there are 7 characteristics that help to decide that something is living. We use the mnemonic MRS GREN for this:
Movement - e.g. a leaf turning towards the light
Respiration - converting food into energy
Sensitivity- e.g plants know which way is up (so they don't grow their roots up and leaves down)
Growth - all living things must start out small and grow bigger
Reproduction - nothing lives forever, so it must reproduce for its kind to survive
Excretion - means the giving off of waste
Nutrition (or feeding)
Because all living things on Earth are made of cells, sometimes you see this changed to MRS C GREN where the "C" stands for cells. However, there may be types of life on other planets that are not based on cells.
Life Functions crossword Life functions cloze exercise
Classification
Imagine if you went to a shop and it sold absolutely anything: fertilizer, chicken wings, pool cleaner, bulldozers, carpet, perfume, turbans, broomsticks, moth repellent, rebreather, x-ray machine.....
However, it is not arranged in any order at all - it is completely random.
The shop might have what you want - but would you ever find it?
For this reason, we tend to break down our shops into groups (food, clothing, hardware, furniture etc) then within each store have the goods further organised.
Scientists also classify the world - different rocks, chemicals and living things.
Often, scientists will use a key to classify things. A key is a series of yes/no questions that leads to a particular answer. Keys can be used for classifying things and for other jobs such as diagnosing a medical condition.
Early attempts to classify living things were based on such things as their lifestyle - bats were classified with birds, dolphins were grouped with fish. As people started to take more notice of the way living things are put together, A Swedish botanist called Carolus Linnaeus invented a "taxonomy" of grouping things together on the basis of their similar features e.g. dolphins were classified into the same group as bats and humans on the basis of their warm blood and milk-producing glands (mammary glands). This is called Linnean classification. It is still used today in a modified form, but scientists in the 21st Century are using molecular genetics rather than similar features to group things together.
A more modern view of classification
In the 21st Century we have begun to use new tools provided by genetics to classify living things in a slightly different way. This way (called a phylogenetic tree) is basically like a family tree, with each branch separation being the last common ancestor between two types of organism. An example of a phylogenetic tree is shown below. Some branches have more than two divisions, either because scientists aren't sure of the exact common ancestor or because this tree is too simple to show it.
It is likely that if you do future work in biology you will use classification based on this model
The Microscope
Microscopes are devices for looking at objects too small for the eye to see. There are several sorts. The diagram below is a monocular (one lens) transmitted light microscope, which is the type used to look at slides. Objects on slides are thin enough that light can be shone through them.
The magnification of a microscope is calculated by multiplying the eyepiece power by the objective lens power. For example, a 4 x eypiece and a 10 x objective gives a 40x magnification. A magnification of 40x means that an object 0.5 mm long will appear to be 40 times larger, or 2 cm long.
Microscope Label exercise - download, complete and put in your Google Drive
How living things are put together
All known living things are made of cells. Some living things are made of a single cell (termed unicellular organisms). An example is bacteria.
Other living things - all of the kingdoms of plants and animals - are made of multiple cells and are termed multicellular organisms. The fungi and protist kingdoms contain both unicellular and multicellular members.
The cells of multicellular organisms are grouped together at different levels, a bit like the whole domain of living organisms are grouped into species, genus, family, class, order, phylum and kingdom.
At the lowest level is a single cell e.g.a cell on the very outside front part of your eye
This cell will be part of a set of identical cells cells, called tissue (in this case, corneal epithelial tissue)
Different tissues group together to make an organ e.g. the cornea of the eye
A group of organs that work together to perform a task make up an organ system e.g. the eye/vision system
Other systems in the human body include the cardiovascular system, the respiratory system, the digestive system, the nervous system, the musculo-skeletal system, the reproductive system, the endocrine system.
We are next going to look at some organs and organ systems in more detail: the heart, lungs and kidneys.
The Circulatory SystemYour blood carries oxygen and nutrients to the organs of your body, and carries away carbon dioxide and waste.Your blood is pumped by the heart. Oxygen rich blood leaves the heart via the arteries, and the carbon dioxide rich blood is carried back to your heart in veins.
Oxygenated blood is usually brighter red than the blood in your veins. Blood in the veins is often depicted as blue in diagrams, though if you see someone bleeding the vein blood (venous blood) is still red, but is darker than arterial blood. Arteries also 'pulse' in time with your heartbeat because they get the rush of blood directly from the heart. Your veins will sometimes look a bit blue under your skin e.g. on the inside of your writs.
The heart is divided into four chambers.Newly oxygenated blood from the lungs is given a squeeze to send it out to the body. When this happens, the valve to the chamber back to the lungs closes. This is to stop the blood being pushed back to the lungs.Once the blood reaches the tiny capillaries in the head, trunk, arms and legs and so on it gives up its oxygen and picks up carbon dioxide. Pushing it through the small vessels causes the blood to lose most of its pressure, which is why there is no pulse in your veins.It takes pressure to push the blood through the tiny capillaries in the lungs, so the other half of the heart takes the de-pressurised blood and squeezes it again to go through the lungs.
You can see how this works below in the animation on the leftt.On an iPad you can download the free app "Vir tual Heart', which is labelled and shows structure and beating
Notice the the left of the heart on the diagram is on your right. Imagine you are looking at someone else facing you - their left is on your right and vice versa. The "left" and "right" is the left and right side of the person whose heart it is.
the left side of the heart takes oxygenated blood from the lungs in the atrium, and pumps it through the body with the ventricle
the right side of the heart takes deoxygenated blood from the body in the atrium, and pumps it through the lungs with the right ventricle
valves ensure the blood doesn't flow 'backwards' when the heart muscle squeezes
The respiratory system
The purpose of the respiratory system is to provide the body with oxygen and remove carbon dioxide. Oxygen and carbon dioxide are carried around the body in the blood.
The process of the blood getting oxygen from air and giving up carbon dioxide to the air is called gas exchange. The lungs are arranged in the way they are to give the maximum possible space for this to happen. In order to do this, air passes through many branching channels called bronchi. As the bronchi repeatedly divide into more branches, the number of branches increases. The smaller branches are called bronchioles. Eventually the branches reach small sacs called alveoli, where gas exchange actually occurs. There are millions of these.
The alveoli are surrounded by tiny blood vessels, bringing oxygen-poor blood from the right ventricle of the heart. After gas exchange, the blood is oxygen rich and passes to the left atrium of the heart and from there into the left ventricle for a 'pressure boost' into the body.
At the bottom of the lungs is a muscle called the diaphragm. This pulls down to pull air into the lungs. Air enters through the mouth and nose and then passes down the trachea into the bronchi.
The pleura is a layer that allows the lungs to move against the ribs and helps keep the suction that allows the diaphragm to do its work.
Bronchi can become inflamed. This is called bronchitis. A common complication is that the muscles around the bronchi squeeze and make the air channels narrower, making it hard to breathe. This also happens in an asthma attack.
The excretory system
Body processes produce wastes. Some of these are breathed out (carbon dioxide in your breath) but most of the body's waste products are passed out dissolved in water in a liquid called urine.
Urine is produced by organs called the kidneys, whose job it is to filter out waste products from the blood. Kidneys also help regulate the amount of water and salt in your blood.
Blood enters the kidney through an artery, is filtered and is removed through a vein. Water is taken out, along with dissolved wastes, and passes down the ureters for temporary storage in the bladder. When the bladder is full the stored urine is released through the urethra.
One of the main wastes in urine is a nitrogen compound called urea, which is actually useful as a nitrogen fertiliser for plants.